I've seen some comments about how poorly Daz auto follows clothing, especially around large breasts. A simple fix for those that don't know is 'smoothing iteration' in the parameters tab for the garment. Crank it up to 12 or so( play around). It's not perfect but it'll get rid of most under boob. Poke through can be a problem so I recommend Mesh Grabber to tug on those spots.
Below is a pic showing the difference. If the garment does not have that option go to 'edit-object-geometry-add smoothing modifier' to add it. The top on the left has iterations set at 18. The one on the right is default at 2.
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